diff --git a/Customizations/JSON/LayoutConfig.ts b/Customizations/JSON/LayoutConfig.ts
index e76c68ac8..511f1ff18 100644
--- a/Customizations/JSON/LayoutConfig.ts
+++ b/Customizations/JSON/LayoutConfig.ts
@@ -95,7 +95,7 @@ export default class LayoutConfig {
             }
         );
         this.defaultBackgroundId = json.defaultBackgroundId;
-        this.layers = LayoutConfig.ExtractLayers(json, this.units, official);
+        this.layers = LayoutConfig.ExtractLayers(json, this.units, official, context);
 
         // ALl the layers are constructed, let them share tags in now!
         const roaming: { r, source: LayerConfig }[] = []
@@ -160,12 +160,12 @@ export default class LayoutConfig {
 
     }
 
-    private static ExtractLayers(json: LayoutConfigJson, units: Unit[], official: boolean): LayerConfig[] {
+    private static ExtractLayers(json: LayoutConfigJson, units: Unit[], official: boolean, context: string): LayerConfig[] {
         const result: LayerConfig[] = []
 
         json.layers.forEach((layer, i) => {
             if (typeof layer === "string") {
-                if (AllKnownLayers.sharedLayersJson[layer] !== undefined) {
+                if (AllKnownLayers.sharedLayersJson.get(layer) !== undefined) {
                     if (json.overrideAll !== undefined) {
                         let lyr = JSON.parse(JSON.stringify(AllKnownLayers.sharedLayersJson[layer]));
                         const newLayer = new LayerConfig(Utils.Merge(json.overrideAll, lyr), units, `${json.id}+overrideAll.layers[${i}]`, official)
@@ -176,7 +176,8 @@ export default class LayoutConfig {
                         return
                     }
                 } else {
-                    throw "Unknown fixed layer " + layer;
+                    console.log("Layer ", layer," not kown, try one of", Array.from(AllKnownLayers.sharedLayers.keys()).join(", "))
+                    throw `Unknown builtin layer ${layer} at ${context}.layers[${i}]`;
                 }
             }
 
@@ -195,9 +196,9 @@ export default class LayoutConfig {
                 names = [names]
             }
             names.forEach(name => {
-                const shared = AllKnownLayers.sharedLayersJson[name];
+                const shared = AllKnownLayers.sharedLayersJson.get(name);
                 if (shared === undefined) {
-                    throw "Unknown fixed layer " + name;
+                    throw `Unknown shared/builtin layer ${name} at ${context}.layers[${i}]. Available layers are ${Array.from(AllKnownLayers.sharedLayersJson.keys()).join(", ")}`;
                 }
                 // @ts-ignore
                 let newLayer: LayerConfigJson = Utils.Merge(layer.override, JSON.parse(JSON.stringify(shared))); // We make a deep copy of the shared layer, in order to protect it from changes
diff --git a/assets/layers/surveillance_camera/surveillance_camera.json b/assets/layers/surveillance_camera/surveillance_camera.json
index 77fed82af..7a6a4248c 100644
--- a/assets/layers/surveillance_camera/surveillance_camera.json
+++ b/assets/layers/surveillance_camera/surveillance_camera.json
@@ -422,19 +422,19 @@
     }
   ],
   "icon": {
-    "render": "./assets/themes/surveillance_cameras/logo.svg",
+    "render": "./assets/themes/surveillance/logo.svg",
     "mappings": [
       {
         "if": "camera:type=dome",
-        "then": "./assets/themes/surveillance_cameras/dome.svg"
+        "then": "./assets/themes/surveillance/dome.svg"
       },
       {
         "if": "_direction:leftright=right",
-        "then": "./assets/themes/surveillance_cameras/cam_right.svg"
+        "then": "./assets/themes/surveillance/cam_right.svg"
       },
       {
         "if": "_direction:leftright=left",
-        "then": "./assets/themes/surveillance_cameras/cam_left.svg"
+        "then": "./assets/themes/surveillance/cam_left.svg"
       }
     ]
   },
diff --git a/assets/themes/artwork/artwork.json b/assets/themes/artwork/artwork.json
index 454ff9eac..feb957abc 100644
--- a/assets/themes/artwork/artwork.json
+++ b/assets/themes/artwork/artwork.json
@@ -429,4 +429,4 @@
       ]
     }
   ]
-}
+}
\ No newline at end of file
diff --git a/assets/themes/campersite/campersite.json b/assets/themes/campersite/campersite.json
index 63192c55b..d458d8085 100644
--- a/assets/themes/campersite/campersite.json
+++ b/assets/themes/campersite/campersite.json
@@ -38,13 +38,13 @@
     "nb_NO"
   ],
   "maintainer": "joost schouppe",
-  "icon": "./assets/themes/campersites/caravan.svg",
+  "icon": "./assets/themes/campersite/caravan.svg",
   "version": "0",
   "startLat": 43.14,
   "startLon": 3.14,
   "startZoom": 14,
   "widenFactor": 0.05,
-  "socialImage": "./assets/themes/campersites/Bar%C3%9Fel_Wohnmobilstellplatz.jpg",
+  "socialImage": "./assets/themes/campersite/Bar%C3%9Fel_Wohnmobilstellplatz.jpg",
   "layers": [
     {
       "id": "caravansites",
@@ -522,7 +522,7 @@
         "reviews"
       ],
       "icon": {
-        "render": "circle:white;./assets/themes/campersites/caravan.svg",
+        "render": "circle:white;./assets/themes/campersite/caravan.svg",
         "mappings": [
           {
             "if": {
@@ -530,7 +530,7 @@
                 "fee=no"
               ]
             },
-            "then": "circle:white;./assets/themes/campersites/caravan_green.svg"
+            "then": "circle:white;./assets/themes/campersite/caravan_green.svg"
           }
         ]
       },
@@ -862,7 +862,7 @@
         }
       ],
       "icon": {
-        "render": "circle:white;./assets/themes/campersites/sanitary_dump_station.svg"
+        "render": "circle:white;./assets/themes/campersite/sanitary_dump_station.svg"
       },
       "width": {
         "render": "8"
diff --git a/assets/themes/cycle_infra/cycle_infra.json b/assets/themes/cycle_infra/cycle_infra.json
index 6f1222ccf..5752938eb 100644
--- a/assets/themes/cycle_infra/cycle_infra.json
+++ b/assets/themes/cycle_infra/cycle_infra.json
@@ -976,7 +976,6 @@
           ]
         }
       ],
-      "hideUnderlayingFeaturesMinPercentage": 0,
       "icon": {
         "render": "./assets/themes/cycle_infra/bicycleway.svg"
       },
diff --git a/assets/themes/cyclestreets/cyclestreets.json b/assets/themes/cyclestreets/cyclestreets.json
index a09314b9d..a5a56c7cc 100644
--- a/assets/themes/cyclestreets/cyclestreets.json
+++ b/assets/themes/cyclestreets/cyclestreets.json
@@ -279,4 +279,4 @@
       ]
     }
   ]
-}
+}
\ No newline at end of file
diff --git a/assets/themes/fruit_trees/fruit_trees.json b/assets/themes/fruit_trees/fruit_trees.json
index bf12bbeca..60d6e8a23 100644
--- a/assets/themes/fruit_trees/fruit_trees.json
+++ b/assets/themes/fruit_trees/fruit_trees.json
@@ -170,4 +170,4 @@
     }
   ],
   "roamingRenderings": []
-}
+}
\ No newline at end of file
diff --git a/assets/themes/surveillance/surveillance.json b/assets/themes/surveillance/surveillance.json
index 62c17e76a..6090c3eee 100644
--- a/assets/themes/surveillance/surveillance.json
+++ b/assets/themes/surveillance/surveillance.json
@@ -25,7 +25,7 @@
     "zh_Hant"
   ],
   "maintainer": "",
-  "icon": "./assets/themes/surveillance_cameras/logo.svg",
+  "icon": "./assets/themes/surveillance/logo.svg",
   "version": "0",
   "startLat": 0,
   "startLon": 0,